A072745 Product of the members of pairs of primes (p, q) with p < q and such that, for some integer k, (p+q)/2 = 2^k and p > 2^(k-1).

15, 55, 247, 799, 943, 4087, 14359, 14863, 15943, 51847, 56887, 59911, 62287, 64807, 65311, 200143, 208783, 234919, 245503, 255583, 259543, 260119, 262063, 848767, 869647, 884551, 960367, 974047, 977287, 983551, 1003207, 1026967

Offset: 1

Author

Reinhard Zumkeller, Jul 08 2002

Keywords

• nonn

Crossrefs

Cf. A072742, A072743, A072744.

Programs

PARI

listkp(k) = {my(list = List()); forprime(p=2^(k-1)+1, 2^k, my(q=2^(k+1)-p); if ((q>p) && isprime(q), listput(list, q*p));); Vec(list);}
upto(k) = {my(list = List()); for (i=1, k, my(klist = listkp(i)); if (#klist, for (j=1, #klist, listput(list, klist[j])));); Vec(list);}
upto(11) \\ Michel Marcus, Jan 22 2022

Formula

a(n) = A072742(n) * A072743(n).

Extensions

Name edited by Michel Marcus, Jan 22 2022